System and method for unbalanced relay-based wireless communications

ABSTRACT

A method and system for wireless communication with a mobile device in which wireless communication is established with the mobile device. A base station is used to transmit directly to the mobile device in a downlink direction. A relay node is used to transmit to the base station communications received in an uplink direction from the mobile station. The relay node relays at least a portion of the uplink traffic received from the mobile station to the base station.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. National Stage patentapplication Ser. No.: 12/092,764, filed May 6, 2008, which is aSubmission Under 35 U.S.C. §371 for U.S. National Stage PatentApplication of International Application Number: PCT/CA2006/001843,filed Nov. 10, 2006, entitled SYSTEM AND METHOD FOR UNBALANCEDRELAY-BASED WIRELESS COMMUNICATIONS, which is related to and claimspriority to U.S. patent application Ser. No.: 60/735,767, filed Nov. 12,2005, the entirety of all of which are incorporated herein by reference.

STATEMENT OF THE TECHNICAL FIELD

The present invention relates to the field of wireless communicationsand more particularly to a method and system for providingcommunications using wireless relay networks in an unbalanced uplink anddownlink arrangement.

DESCRIPTION OF THE RELATED ART

As the demand for high speed broadband networking over wirelesscommunication links increases, so too does the demand for differenttypes of networks that can accommodate high speed wireless networking.For example, the deployment of Institute of Electrical and ElectronicEngineers (“IEEE”) 802.11 wireless networks in homes and business tocreate Internet access “hot spots” has become prevalent in today'ssociety. However, these IEEE 802.11-based networks are limited inbandwidth as well as distance. For example, maximum typical throughputfrom a user device to a wireless access point is 54 MB/sec. at a rangeof only a hundred meters or so. In contrast, while wireless range can beextend through other technologies such as cellular technology, datathroughput using current cellular technologies is limited to a fewMB/sec. Put simply, as the distance from the base station increase, theneed for higher transmission power increases and the maximum data ratetypically decreases. As a result, there is a need to support high speedwireless connectivity beyond a short distance such as within a home oroffice.

As a result of the demand for longer range wireless networking, the IEEE802.16 standard was developed. The IEEE 802.16 standard is oftenreferred to as WiMAX or less commonly as WirelessMAN or the AirInterface Standard. This standard provides a specification for fixedbroadband wireless metropolitan access networks (“MANs”) that use apoint-to-multipoint architecture. Such communications can beimplemented, for example, using orthogonal frequency divisionmultiplexing (“OFDM”) communication. OFDM communication uses a spreadspectrum technique distributes the data over a large number of carriersthat are spaced apart at precise frequencies. This spacing provides the“orthogonality” that prevents the demodulators from seeing frequenciesother than their own.

The IEEE 802.16 standard supports high bit rates in both uploading toand downloading from a base station up to a distance of 30 miles tohandle such services as VoIP, IP connectivity and other voice and dataformats. Expected data throughput for a typical WiMAX network is 45MBits/sec. per channel. The 802.16e standard defines a media accesscontrol (“MAC”) layer that supports multiple physical layerspecifications customized for the frequency band of use and theirassociated regulations. This MAC layer uses protocols to ensure thatsignals sent from different stations using the same channel do notinterfere with each other “collide”. However, the 802.16e standard doesnot provide support for multi-hop networks.

IEEE 802.16 networks, such as IEEE 802.16j networks, can be deployed asmulti-hop networks from the subscriber equipment to the carrier basestation. In other words, in multi-hop networks, the mobile station cancommunicate with the base station directly or through an intermediatedevice.

As noted above, the IEEE 802.16e standard does not support multi-hopnetworks. This standard also does not address improving the uplink(mobile station to base station peak to average power ratio (“PAPR”)while reducing the imbalance in the uplink to downlink (base station tomobile station) budget. PAPR issues result from the fact that the mobilestation can not transmit with as much power as the base station andbecause the mobile device is often in motion. The resultant imbalance inthe uplink (“UL”) to downlink (“DL”) budget results from the differencein the PAPRs in the UL and DL directions. For example the typical uplinkPAPR for an orthogonal frequency division multiplexing (“OFDM”) wirelesscommunication system is less than the PAPR for the downlink. Onesolution to addressing these problems is the use of a relay. However,while the IEEE 802.16j standard for supporting multi-hop networks hasbeen proposed, this standard also does not provide a method orarrangement for improving PAPR or a way to reduce the imbalance in theuplink to downlink budget. Further, the use of a relay in the DL isinherently complex. As such, it is desirable to have an arrangement thatuses a relay to improve the uplink PAPR while reducing the imbalance inthe uplink to downlink budget. It is further desirable to provide thisarrangement in a manner that does not require a complex relay or set ofimplantation details and protocols.

SUMMARY OF THE INVENTION

The present invention advantageously provides a method and system thatuses unbalanced wireless communications between a mobile station and thebase station through the use of a stationary wireless relay. Thisunbalanced communication is implemented by using the relay only to relaytransmissions in the UL direction. In the DL direction, the base stationtransmits directly to the mobile station without the use of the relay.

In accordance with one aspect, the present invention provides a methodfor wireless communication with a mobile device in which wirelesscommunication is established with the mobile device. A base station isused to transmit directly to the mobile device in a downlink direction.A relay node is used to transmit to the base station communicationsreceived in an uplink direction from the mobile station. The relay noderelays at least a portion of the uplink traffic received from the mobilestation to the base station.

In accordance with another aspect, the present invention provides asystem for wireless communications with a mobile station in which a basestation engages in wireless communication directly with the mobilestation in a downlink direction. A relay node engages in wirelesscommunication with the mobile station in an uplink direction and relaysat least a portion of the uplink traffic received from the mobilestation to the base station.

In accordance with still another aspect, the present invention providesa base station for wireless communications with a mobile station and arelay node. The base station includes a transmitter and a receiver. Thetransmitter directly engages in communications with the mobile stationand the relay node in a downlink direction. The receiver receiveswireless communications from the relay node in an uplink direction. Themobile station communicates with the base station in the uplinkdirection via the relay node.

Additional aspects of the invention will be set forth in part in thedescription which follows, and in part will be obvious from thedescription, or may be learned by practice of the invention. The aspectsof the invention will be realized and attained by means of the elementsand combinations particularly pointed out in the appended claims. It isto be understood that both the foregoing general description and thefollowing detailed description are exemplary and explanatory only andare not restrictive of the invention, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute partof this specification, illustrate embodiments of the invention andtogether with the description, serve to explain the principles of theinvention. The embodiments illustrated herein are presently preferred,it being understood, however, that the invention is not limited to theprecise arrangements and instrumentalities shown, wherein:

FIG. 1 is a diagram of a system constructed in accordance with theprinciples of the present invention;

FIG. 2 is an information flow diagram of a mobile station entry processin accordance with the principles of the present invention;

FIG. 3 is an information flow diagram of an embodiment of uplink HARQoperation in accordance with the principles of the present invention;

FIG. 4 is an information flow diagram of another embodiment of uplinkHARQ operation in accordance with the principles of the presentinvention;

FIG. 5 is an information flow diagram of a bandwidth request, periodicranging and handoff ranging process in accordance with the principles ofthe present invention;

FIG. 6 is a table of an exemplary arrangement of a MAC layer managementresponse report message constructed in accordance with the principles ofthe present invention; and

FIG. 7 is a table of an exemplary arrangement of a MAC layer indicationmanagement message constructed in accordance with the principles of thepresent invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As an initial matter, reference may be made herein to “data plane” and“control plane.” In general, the control plane includes configured orsignaled information that determines the overall behavior, mappings,resource allocation and forwarding parameters that can be applied to allconnection frames or frames of a service class. Such information istypically established and used to set up the network devices before anypayload traffic is transmitted. Data plane refers to the frameprocessing functions that typically take place in real-time on aframe-by-frame basis. In accordance with embodiments of the invention,various MAC control plane embodiments for use in wireless networks usingrelays are described. While certain embodiments are discussed in thecontext of wireless networks operating in accordance with the IEEE802.16 broadband wireless standard, which is hereby incorporated byreference, the invention is not limited in this regard and may beapplicable to other broadband networks including those operating inaccordance with other OFDM orthogonal frequency division (“OFDM”)-basedsystems including the 3rd Generation Partnership Project (“3GPP”) and3GPP2 evolutions. Similarly, the present invention is not limited solelyto OFDM-based systems and can be implemented in accordance with othersystem technologies, e.g., CDMA.

Referring now to the drawing figures in which like reference designatorsrefer to like elements, there is shown in FIG. 1, a system constructedin accordance with the principles of the present invention anddesignated generally as “10.” System 10 includes base station 12, relaynode 14 and mobile station 16. Base stations 12 communicate with oneanother and with external networks, such as the Internet (not shown),via carrier network 18. Base stations 12 engage in wirelesscommunication with relay nodes 14 and/or mobile stations 16. Similarly,mobile stations 16 engage in wireless communication with relay nodes 14and/or base stations 12.

Base station 12 can be any base station arranged to wirelesslycommunicate with relay nodes 14 and/or mobile stations 16. Base stations12 include the hardware and software used to implement the functionsdescribed herein to support the MAC control plane functions. Basestations 12 include a central processing unit, transmitter, receiver,I/O devices and storage such as volatile and nonvolatile memory as maybe needed to implement the functions described herein. As is describedbelow in detail, the transmitter directly engages in communications withthe mobile station 16 and the relay node 14 in a downlink direction. Thereceiver receives wireless communications from the relay node 14 in anuplink direction. The mobile station 16 communicates with the basestation 12 in the uplink direction via the relay node 14.

Mobile stations 16 can be any mobile station including but not limitedto a computing device equipped for wireless communication, cell phone,wireless personal digital assistant (“PDA”) and the like. Mobilestations 16 also include the hardware and software suitable to supportthe MAC control plane functions needed to engage in wirelesscommunication with base station 12 either directly or via a relay node14. Such hardware can include a receiver, transmitter, centralprocessing unit, storage in the form of volatile and nonvolatile memory,input/output devices, etc.

Relay node 14 is used to facilitate wireless communication betweenmobile station and base station 12 in the uplink (mobile station 16 tobase station 12) and/or the downlink (base station 12 to mobile station16). A relay node 14 configured in accordance with the principles of thepresent invention includes a central processing unit, storage in theform of volatile and/or nonvolatile memory, transmitter, receiver,input/output devices and the like. Relay node 14 also includes softwareto implement the MAC control plane functions described herein. Of note,according to an embodiment, base stations 12 and relay nodes 14implemented in accordance with the principles of the present inventionare fixed, i.e. non-moving devices, but the invention is not limited tosuch. It is contemplated that these devices may move. Mobile stations 16can be fixed, stationary or moving.

FIG. 1 shows unbalanced relay operation. As is shown by the dashed linesin FIG. 1, mobile station 16 communicates with base station 12 via relaynode 14 in the uplink direction only. Base station 12 communicates inthe downlink direction directly with mobile station 16. Base station 12is also shown as engaging in bi-directional communication with relaynode 14 so that base station 12 can receive data from mobile station 16via relay node 14 and engage in MAC control plane communications withrelay node 14. The unbalanced relay arrangement shown in FIG. 1 relievesmobile station 16 from concerns over the peak to average power ratio(“PAPR”) and reduces the unbalance in the downlink (“DL”)/uplink (“UL”)link budget. Such occurs, for example, because the base station 12 iscapable of much higher power transmission and is much more sensitive onthe receiving side than mobile station 16 for wireless communicationssuch as orthogonal frequency division multiplexed (“OFDM”)communications. In other words, within a given area supported by basestation 12, using an unbalanced communication arrangement such as thatshown in FIG. 1 allows a more even transmission power arrangement on theuplink and downlink because mobile station 16 can communicate with relaynode 14 in the UL direction, which is presumably closer to mobilestation 16 than base station 12 (at least for purposes of the presentinvention). In addition, the present arrangement as is shown in FIG. 1does not require any implementation or programmatic software changes orenhancements to mobile station 16 or base station 12 with respect todownlink communication because such is accomplished directly betweenbase station 12 and mobile stations 16 as is known in the art.

In the uplink direction, base station 12 schedules uplink transmissionfor mobile station 16 and relay node 14. Mobile station 16 makes itsuplink transmission which is received and decoded by relay node 14.Relay node 14 relays the traffic to base station 12. Instead of rangingto base station 12, mobile station 16 ranges to relay node 14. As usedherein, the term “ranging” is used as understood by one of ordinaryskill in the art. “Ranging” refers to the process used in OFDM wirelesscommunications to adjust the arrival time for different mobile stations16 communicating with a single base station 12. The ranging process isalso used to establish the transmit power for mobile station 16. Theranging process is analogous to a “handshake” between mobile station 16and its communication partner, i.e. relay node 14, in the uplinkdirection.

The inclusion of relay node 14 in the embodiment shown in FIG. 1 istransparent to mobile station 16. In other words, because DLcommunication comes from base station 12 and not relay node 14, mobilestation does not know that its UL communication is not directly withbase station 12 and is instead with relay node 14. This arrangementprovides a suitable low-cost, fixed relay node implementationembodiment. With respect to MAC enhancement, no additional MACcapability, e.g., downlink re-fragmentation, scheduling, etc., is neededin this embodiment. Such management messages might include, for example,a relay node report message that allows a relay node to report rangingcodes, channel quality index channel and downlink hybrid automatedrepeat request (“HARQ”) error control method acknowledgement channelsand combined uplink traffic HARQ status messages for multiple mobilestations 16. Another MAC management message may include a message sentby base station 12 to relay node (“RN”) 14 which enables base station 12to indicate the uplink connection identifications supportedcommunication sessions to a regional node for monitoring and relaying.

Because base station 12 communicates directly with mobile station 16 inthe downlink (“DL”) direction, no change to DL connection andcommunication processes is required from current standards and protocolssuch as those used for orthogonal frequency division multiplexing(“OFDM”) or those proposed under IEEE 802.16. In the uplink (“UL”)direction, relay node 14 is used for communication as noted above. Inthe UL case, base station 12 schedules the UL transmission. At mobilestation 16 transmits in the UL direction, and relay node 14 decodes theUL traffic received from mobile station 16 and relays the traffic tobase station 12. Mobile station 14 “ranges” to relay node 14 with theranging being controlled by base station 12.

In terms of operation, the present invention advantageously provides anoperation that is transparent to mobile station 16, thereby allowingcurrent mobile stations to operate with relay node 14. Enhancement tothe MAC layer is provided to support relay nodes 14. However, while thepresent invention provides new management messages to facilitateoperation between mobile stations 16 and relay nodes 14, and betweenrelay node 14 and base station 12, the present invention allows existingrelay node pilot design, downlink re-fragmentation, scheduling, etc., tobe used.

The present invention provides an arrangement to facilitate initialaccess of mobile station 16 into a wireless communication network havingrelay node 14. Arrangements for UL traffic transmission constructed inaccordance with the principles of the present invention as well as thoserelated to UL control channel payload relay are described. Bandwidthrequest, periodic ranging and handoff (“HO”) ranging for system 10 arealso described. Finally, new MAC management messages to support thearrangement shown in FIG. 1 are described.

The initial access process is used to allow base station 12 to knowwhich relay node 14 is supporting mobile station 16. Further, it iscontemplated that more than one relay node 14 can support a mobilestation 16. The mobile station 16 initial access process is describedwith reference to the information flow diagram shown in FIG. 2.Initially, mobile station 16 performs DL synchronization and reads theUL-MAP transmitted by base station 12 (Step S100). Relay node 14 alsoreceives and reads the UL-MAP. Mobile station 16 then sends an initialranging code to base station 12 (Step S102). The initial ranging code isalso received by relay node 14 (Step S102). One or more relay nodes 14detect the transmission of the initial ranging code and report the sameto base station 12 through a response MAC management message (StepS104). As used herein, the MAC management response message is indicatedas (“RN_RN-REP”). The RN_RN-REP MAC management message includes rangingcode attributes such as those used for power and timing adjustment toallow mobile station 16 to range to relay node 14.

Base station 12 reserves UL resources for each relay node 14 to allowrelay node 14 to send the RN_RN-REP MAC management response message.Base station 12 determines the capturing relay node 14 (defined hereinas the “C-RN”) that the C-RN 14 will be responsible for capturing ULtransmission for the mobile station 16 (Step S106). Base station 12informs the C-RN 14 using an indication message, defined herein as an“RN_RN-ND” message. Also in Step S106, base station 12 informs mobilestation 16 of the ranging code and power and timing adjustment through aranging response MAC management message, defined herein as a “RNG-RSP”message, that is sent along with the UL-MAP. Ranging continues in StepS108 in which mobile station 16 sends an initial ranging code to basestation 12. As with Step S102, relay node 14 also receives the initialranging code and sends an RN_RN-REP reporting message to base station 12(Step S110) once relay node 14 determines the power and timingadjustment. In other words, power and time adjustment information istransmitted by relay node 14 to base station 12 using an RN_RN-REPmanagement message. As shown in Steps S114 and S116, the procedurecontinues until the time and power of mobile station 16 transmission arealigned. Of note, relay node 14 monitors the UL-MAP for UL rangingregion information elements. Once initial ranging is complete, basestation 12 transmits the UL-MAP and the code division multiple access(“CDMA”) allocation information to mobile station 16 (Step S118). Thistransmission is monitored by relay node C-RN14. From time to time,mobile station 16 sends a ranging request message, (shown as Step S120)to ensure power and time alignment. This message is monitored by relaynode 14.

Base station 12 transmits the UL-MAP, RNG-RSP message to mobile station16 along with the assigned UL connection IDs (“CID”) (Step S122). CIDrefers to identifications corresponding to a communication sessionbetween mobile station 16 and base station 12. The UL-MAP includesinformation elements (“IE”) which define what communication resourcesare allocated to which mobile stations. Base station 12 also sends theUL-MAP and informs relay node 14 of all UL CIDs assigned to mobilestation 16 using a base station indication message (defined as“RN_BS-IND”) (Step S124). This arrangement advantageously enables theC-RN 14 to monitor the

UL transmission of mobile station 16 without requiring other DL messages(with the exception of the DL-MAP and UL-MAP). As is readily observablein FIG. 2, the entire initial access procedure is transparent to mobilestation 16, i.e., mobile 16 ranges to an RN 14 as it would range tostation 12.

Once the mobile station 16 initial access procedure has been completed,mobile station 16 is able to engage in transmission of uplink traffic.As noted above, with respect to initial access, C-RN 14 obtains the ULCIDs of mobile station 16 through the RN_BS-IND MAC message. C-RN 14monitors the UL-MAP for uplink resource allocation of mobile station 16.

Because C-RN 14 monitors the UL-MAP and knows what resources areallocated to what mobile stations, and knows the CIDs of the mobilestations, C-RN 14 can detect and relay UL transmission of mobile station16. The present invention also supports UL hybrid automated repeatrequest (“HARQ”) operation. The present invention provides twoembodiments for UL HARQ operation.

The first embodiment for UL HARQ operation is described with referenceto the information flow diagram of FIG. 3. In accordance with the firstHARQ embodiment, one or more transmissions received from a mobilestation 16 are combined by C-RN 14 and reported to base station 12. Basestation 12 creates the UL HARQ acknowledgement/no acknowledgement(“ACK/NACK”) and transmits the UL HARQ ACK/NACK message to mobilestations 16. Regarding resource assignment for C-RN 14 with respect torelaying UL traffic, for this embodiment, C-RN 14 is allocated enoughchannel resources by base station 12 for successful transmission. Thisarrangement may waste some channel resources and may delay transmissionby one or more frames.

Referring to FIG. 3 as an example of UL HARQ operation for the firstembodiment, base station 12 transmits the UL-MAP which is received byC-RN 14 and mobile station 16 (Step S126). Mobile station 16 transmitsunicast traffic on the uplink (Step S128). The unicast traffic isreceived by C-RN 16 in some corrupt/invalid form and C-RN 14 transmitsan RN_RN-REP management control message indicating NACK to base station12 (Step S130). Base station 12 transmits the UL-MAP and uplink HARQNACK information element (which is contained in the UL-MAP) to mobilestation 16 (Step S132). That transmission from base station 12 is alsomonitored by C-RN 14. Mobile station 16 retransmits the unicast trafficon its uplink (Step S134). In the case of the example shown in FIG. 3,that transmission is successfully received by C-RN 14 which in turntransmits an R_RN-REP MAC management control message to base station 12followed by the actual relay of the traffic (Step S136). Of note,although a single mobile station 16 is shown in FIG. 3, it is understoodthat, because C-RN 14 is generating the HARQ ACK/NACK, that C-RN 14 cancombine multiple ACK/NACK messages and from multiple mobile stations 16and transmit them in single message to base station 12.

In accordance with the second embodiment for UL HARQ operation, the HARQpackets are combined at base station 12. Such is useful in the casewhere a mobile station 16 has more than one C-RN 14 in a macro ULdiversity arrangement. In accordance with this second embodiment, C-RN14 relays HARQ bits to base station 12 and base station 12 combines andcreates the UL HARQ ACK/NACK message. Resources for C-RN 14 UL unicasttraffic relay are assigned in accordance with this embodiment in anarrangement such that resource is predictable and can be easilyassigned. In other words, unlike the first option, C-RN 14 need notpre-allocate channel resources to ensure successful transmission.

An example of UL HARQ operation in accordance with the second embodimentis described with reference to FIG. 4. FIG. 4 shows two C-RN 14s,labeled (“RN1” and “RN2”) in FIG. 4 for ease of explanation. Initially,base station 12 transmits the UL-MAP to mobile station 14 (Step 138) RN1and RN2 monitor this transmission and understand the resource allocationto mobile station 16. Mobile station 16 transmits unicast traffic on theuplink (Step S140). The signal is received by RN1 and RN2 which in turnrelay the signal to base station 12 (Step S142) without combining. Anycombining is done by base station 12. Accordingly, it is possible thatone of the C-RN 14 devices indicates an ACK while the other indicates aNACK. Base station 12, through the UL-MAP can indicate the HARQ statusto mobile station 16 (Step S144) with the process repeating as necessarywith respect to the transmission or retransmission of traffic (StepsS146 and S148).

The present invention provides an arrangement under which UL controlchannel payload is relayed by C-RN 14 to base station 12. The UL controlchannel is used to facilitate DL transmission and includes a channelquality indication channel (“CQICH”) and a downlink HARQ acknowledgementchannel (DL HARQ ACK CH″). In accordance with the present invention,relay node 14 (C-RN 14) detects the uplink control channelscorresponding to the mobile stations it serves. C-RN 14 combines theinformation carried in the UL control channels received from themultiple mobile station 16 into MAC layer messages to send to basestation 12. Because the uplink resource is used for control channelrelay by C-RN 14 is predictable, the base station 12 can reservewireless communication channel resources for each C-RN to dedicate thisresource for control channel relay.

Periodically, mobile station 16 may send a bandwidth request, or performperiodic ranging or HO ranging. With periodic type requests such asthese, it is noted that the operation of code transmission and capturewith respect to UL-MAP transmission by base station 12 and processing bymobile station 16 are the same as initial ranging, described above. Oncethe code has been captured, C-RN 14 combines the bandwidth request,periodic ranging and HO ranging messages from multiple mobile stations16 and transmits the combined messages to base station 12. Once the codeis captured, operation to process and address the bandwidth request,periodic ranging or HO ranging can proceed as is known in the art, suchas using the IEEE 802.60e standard.

The bandwidth request, periodic ranging and HO ranging process of thepresent invention is described with reference to the information flowdiagram of FIG. 5. Initially, base station 12 transmits the UL-MAP tomobile station 16 (Step 150). UL-MAP transmission is also monitored byC-RN 14. During operation, mobile station 16 transmits a bandwidthrequest, periodic ranging or HO ranging code (Step S152). Thistransmission is received by C-RN 14. C-RN 14 combines the informationrelated to this transmission with other bandwidth request, periodicranging or HO ranging transmissions received from other mobile stations16 (not shown) and generates and transmit a message to base station 12in the form of an RN_RN-REP control message (Step S154). Base station 12transmits a UL-MAP to mobile station 12 which includes an assignment ofresources for further processing relating to the bandwidth request,periodic ranging or HO ranging (Step S156).

The present invention provides MAC management messages to support theoperations described herein. In particular, the RN-RN REP responsemessage described above and the RN_BS IND indication message describedabove are defined herein. Each is discussed in detail.

The RN-RN REP response report message enables the C-RN 14 to report tobase station, (1) the ranging code captured and the timing, frequencyand power level adjustment needed for initial ranging, (2) the CQICHinformation collected from various mobile stations 16, (3) the DL HARQACK information collected from various mobile stations 16, and (4) theuplink traffic relay for the combined HARQ status received from mobilestations 16.

An exemplary arrangement of an RN-RN REP MAC management message isdescribed with reference to FIG. 6. Report message format table 20includes a syntax field 22 and the field size 24, in bits, of thecorresponding field 22. Of note, the field size 24 shown in FIG. 6 ismerely exemplary, it being understood that the field size 24corresponding to each field 22 within the report message can be largeror smaller depending on the desired implementation. As such, the presentinvention is not limited to the specific field size 24 shown in FIG. 6.

In addition, it is contemplated that the report NACK message may includefewer fields 22 and report types as shown in FIG. 6. The report messageincludes a management message type field and a field defining the numberof possible report types for which information is included in the reportmessage. The management message type field is used to indicate that theMAC message is a report message. The report message also includes areport type field to identify the corresponding types of data present inthe report message. For example, where the two bit field indicating thereport type is “00,” the following fields include a four bit field forthe number of the ranging codes captured and, for each captured rangingcode from mobile stations 16, the corresponding ranging code attributes.Where the ranging code is equivalent to an initial ranging code, fieldsare provided for timing adjustment, power level adjustment, offsetfrequency adjustment and ranging status.

Regarding ranging code attributes, for example, the first 8 bits canrepresent the 8 significant bits of the frame number of the OFDM 8 framewhere the mobile station 16 sent the ranging code. Bits 8 through 15 canbe used to indicate the ranging code index that was sent by the mobilestation 16. Bits 16 through 21 can be used to indicate the OFDMsub-channel reference that was used to transmit the code and bits 22through 31 can be used to indicate the OFDM time symbol reference thatwas used to transmit the ranging code. Where the ranging code indexindicates timing adjustment, a signed 32 bit number can be used torepresent the timing adjustment where each unit is specific to thephysical transmission. Where the ranging code index indicates a powerlevel adjustment, the power level adjustment can indicate and offset in0.25 dB increments. Regarding the offset frequency adjustment, theadjustment can be indicated which each adjustment unit is 1 Hz. Finally,the ranging status can be used to indicate whether the uplinktransmission is received within acceptable limits by the C-RN 14.

Where report type is a “01,” indicating, for example, CQICH information,a field is provided to indicate the number of relay nodes for which CQIinformation has been collected, and fields for the reporting the CQIpayload. For example, the CQI collected payload can be a five bit or sixbit field for each mobile station 16 for which CQI has been collected.The CQI payload and ACK payload are listed in the order of a CQICH indexwhich is assigned by C-RN 14 to mobile station 16 being serviced by theC-RN 14.

Where the report type is a “10” indicating the collection of HARQ ACKinformation, a field is provided to indicate the quantity of mobilestation 16 for which HARQ is being reported. Where the report type isindicated as a “11,” indicating for example, the reporting of combinedUL traffic relay HARQ status information, a field is provided toindicate the number of mobile station 16 for which the HARQ status isbeing reported, and a one bit field to report each of the uplink HARQstatus bits. The UL HARQ status used to indicate whether the ULtransmission was received within acceptable limits by the C-RN 14.

The indication MAC management message (RN_BS-IND) is explained withreference to FIG. 7. The indication messages, as discussed above, aresent by base station 12 to C-RNs 14 to enable base station 12 toindicate the UL CIDs to a C-RN 14 for subsequent monitoring and relayingof traffic and management information. In the case where efficientranging is supported, the assigned dedicated ranging resource, i.e.,code index, is included in the indication message to a C-RN 14. Rangingmeans that mobile station 16 initially sends ranging codes to basestation 12 and, if the base station 12 or C-RN/16 needs to makeadjustment, it does so and assigns ranging codes at the same time.

FIG. 7 shows table 26 which provides an exemplary field format for theindication MAC message. Table 26 includes syntax field 28 and field size30. As with the discussion above regarding the report message, thefields and sizes shown are merely exemplary, it being understood thatthe field size is not limited to the size shown in FIG. 7 and thespecific fields and arrangement of the fields shown in syntax column 28are not considered limiting. The MAC type field is used to indicate thatthe MAC message is an indication message (RN_BS_IND). A 4 bit field isalso provided to indicate the number of CIDs for which information isincluded.

For each of the CIDs, the CID is included as well as an indication ofthe number of dedicated ranging resource assignments for each CID. Foreach of the dedicated ranging resource assignments, a code index fieldis provided.

The present invention advantageously provides an imbalanced relay systemwhich parlays the typical high quality transmission associated with thebase station 12 to relay node 14 due to the stationary nature of relaynode 14 which in turn allows a high data rate. As such, relay node 14 isable to combine various messages received from multiple mobile stations16 and transmit those in a single, high data rate, packet to basestation 12. The result is that system designers are relieved fromconcerns over mobile station uplink PAPR, and the DL/UL link budgetimbalance is reduced. The present invention also avoids a situationwhere a relay node 14 would have to re-fragment DL transmission fromrelay node 14 to mobile station 16. Instead, conventional transmissionis used on the DL because the base station's ability to transmit at ahigher power level on the downlink than the mobile station can transmiton the uplink. The UL is preserved. The present invention may thereforeallow the use of OFDM to gain the benefits therefrom, but avoids theneed to implement a complex relay that accommodates both UL and DL relayoperations.

The present invention can be realized in hardware, software, or acombination of hardware and software. Any kind of computing system, orother apparatus adapted for carrying out the methods described herein,is suited to perform the functions described herein.

A typical combination of hardware and software could be a specialized orgeneral purpose computer system having one or more processing elementsand a computer program stored on a storage medium that, when loaded andexecuted, controls the computer system such that it carries out themethods described herein. The present invention can also be embedded ina computer program product, which comprises all the features enablingthe implementation of the methods described herein, and which, whenloaded in a computing system is able to carry out these methods. Storagemedium refers to any volatile or non-volatile storage device.

Computer program or application in the present context means anyexpression, in any language, code or notation, of a set of instructionsintended to cause a system having an information processing capabilityto perform a particular function either directly or after either or bothof the following a) conversion to another language, code or notation; b)reproduction in a different material form. In addition, unless mentionwas made above to the contrary, it should be noted that all of theaccompanying drawings are not to scale. Significantly, this inventioncan be embodied in other specific forms without departing from thespirit or essential attributes thereof, and accordingly, referenceshould be had to the following claims, rather than to the foregoingspecification, as indicating the scope of the invention.

1. A method of operating a relay node in a wireless network to relaycommunications between a mobile device and a base station, the methodcomprising: receiving an initial ranging signal transmitted by themobile device, the initial ranging signal having ranging code attributesassociated therewith; generating a relay node report signal, the relaynode report signal conveying: the ranging code attributes; power dataand timing adjustment data based on the received initial ranging codesignal; and channel quality indication information received from atleast one mobile device; and relaying at least a portion of traffic inone direction only between the mobile station and the base station. 2.The method of claim 1, wherein the one direction is an uplink directionfrom the mobile device to the base station.
 3. The method of claim 1,wherein the one direction is a downlink direction from the base stationto the mobile devices.
 4. The method of claim 2, further comprisingreceiving a relay node indication signal from the base station, therelay node indication signal conveying an uplink connection identifier.5. The method of claim 4, wherein relaying at least a portion of trafficin one direction only between the mobile station and the base stationincludes relaying communications associated with the uplink connectionidentifier between the mobile device and the base station.
 6. The methodof claim 2, wherein generating a relay node report signal includesgenerating a relay node report signal conveying uplink hybrid automatedrepeat request messages received from a plurality of mobile devices. 7.The method of claim 2, wherein the relay node report signal conveys dataindicating whether an uplink transmission received by the relay nodefrom the mobile device was received within acceptable limits.
 8. Themethod of claim 2, wherein the relay report signal conveys dataindicating whether uplink transmissions received by the relay node fromeach of a plurality of mobile devices was received within predeterminedacceptable limits.
 9. The method of claim 2, further comprisingcombining information conveyed in uplink control channels associatedwith multiple mobile devices for transmission to the base station. 10.The method of claim 9, wherein combining information conveyed in uplinkcontrol channels comprises combining the information conveyed in theuplink control channels into media access control (MAC) layer messagesfor transmission to the base station.
 11. A relay node for relayingcommunications between a mobile device and a base station in a wirelessnetwork, the relay node comprising: at least one processor; and at leastone memory device configured to store instructions for execution by theprocessor, the instructions comprising instructions executable: toreceive an initial ranging signal transmitted by the mobile device, theinitial ranging signal having ranging code attributes associatedtherewith; to generate a relay node report signal, the relay node reportsignal conveying: the ranging code attributes; power data and timingadjustment data based on the received initial ranging code signal; andchannel quality indication information received from at least one mobiledevice; and to relay at least a portion of traffic in one direction onlybetween the mobile station and the base station.
 12. The relay node ofclaim 11, wherein the one direction is an uplink direction from themobile device to the base station.
 13. The relay node of claim 11,wherein the one direction is a downlink direction from the base stationto the mobile devices.
 14. The relay node of claim 12, wherein theinstructions further comprise instructions executable to receive a relaynode indication signal from the base station, the relay node indicationsignal conveying an uplink connection identifier.
 15. The relay node ofclaim 14, wherein the instructions executable to relay at least aportion of traffic in one direction only between the mobile station andthe base station include instructions executable to relay communicationsassociated with the uplink connection identifier between the mobiledevice and the base station.
 16. The relay node of claim 12, wherein theinstructions executable to generate a relay node report signal comprisesinstructions executable to generate a relay node report signal conveyinguplink hybrid automated repeat request messages received from aplurality of mobile devices.
 17. The relay node of claim 12, wherein therelay node report signal conveys data indicating whether an uplinktransmission received by the relay node from the mobile device wasreceived within acceptable limits.
 18. The relay node of claim 12,wherein the relay report signal conveys data indicating whether uplinktransmissions received by the relay node from each of a plurality ofmobile devices was received within acceptable limits.
 19. The relay nodeof claim 12, wherein the instructions further comprise instructionsexecutable to combine information conveyed in uplink control channelsassociated with multiple mobile devices for transmission to the basestation.
 20. The relay node of claim 19, wherein the instructionsexecutable to combine information conveyed in uplink control channelscomprise instructions executable to combine the information conveyed inthe uplink control channels into media access control (MAC) layermessages for transmission to the base station.